Piece tensioning device for circular knitting machines for hosiery



June 18, 1957 Filed Oct. 6, 1955 G. PIECE TENSIONIN KNITTING MACHINES FOR HOSIERY 3 Sheets-Sheet l INVENTOR GIUSEPPE MCREDTA ATTORNEY June 18, 1957 G. MORET' I'A PIECE TENSIONING DEVICE FOR CIRCULAR KNITTING MACHINES FOR HOSIERY 3 Sheets-Sheet 2 Filed Oct. 6, 1955 fill/III n "mu/ mun,

m in M IV h V////// INVENTOR GIUSEPPE IGREITA ATTORNEY June 18, 1957 G. MORETTA 2,795,943

PIECE TENSIONING DEVICE FOR CIRCULAR KNITTING MACHINES FOR HOSIERY Filed Oct. 6, 1955 3 Sheets-Sheet 3 aa 6 92 L 51 .--.----lw,+. F 4 I O 8 79 E 90 1 as 86 b 75 'C sa l 81 Boar? 0 x O F|g.6 e 72 s as INVENTOR GIUSEPPE MORETTA ATTORNEY United States Patent PIECE TENSIONING DEVICE FOR CIRCULAR KNITTING MACHINES FOR HOSIERY Giuseppe Moretta, Varese, Italy Application October 6, 1955, Serial No. 538,968

Claims priority, application Italy March 30, 1955 Claims. (Cl. 66149) The present invention relates to circular knitting machines, particularly to circular knitting machines for hosiery, and has for its object to provide an improved construction of tensioning device for keeping fabric knitted by the machine under tension during its formation.

The kind of machine to which the tensioning device tached to the leg of the stocking. Though such tent sioning devices are extremely simple from a constructional standpoint, they suffer from many disadvantages. They cannot be attached to the stockings before the double welt has been completed and attached to the leg of the stocking and it is essential to stop the machine and start it again during such attachment, with a consequent waste of time.

Another disadvantage resides in that the tensioning action of the weight is not uniformly distributed around the whole of the stocking being formed.

To overcome the above mentioned disadvantages it has already been proposed to provide an automatic device which essentially comprises a cylindrical body having means capable of gripping the welt of the stocking, the outside diameter of the cylindrical body being substantially the same as the inside diameter of the tube on which the needle-cylinder is fitted, a supporting member integral with said cylindrical body and extending therebelow, means in said supporting member capable of operating the means for gripping the stocking, means for lifting the assembly comprising said supporting member and said cylindrical body and also means for synchronising the lifting movement with the formation of the welt. This known device is very intricate and suffers from a number ofdisadvantages.

The means for gripping the stocking at the desired instant and the driving means related thereto are very complicated from a constructional standpoint, and the assembly comprising the cylindrical body and the supporting member has a considerable vertical length. As the whole assembly has to be gripped to the stocking during the formation thereof, it follows that the bed of the machine has to be very high and this involves an additional disadvantage in that inspection, maintenance and control of the most important parts of the machine become difficult and inconvenient.

The present invention is concerned with the automatic devices of the type just described and overcomes the previous disadvantages. Furthermore, the device according to the invention has the advantageous construc- 2 tional simplicity which permits particularly positive and safe operation.

According to the present invention there is provided a tensioning device for a circular hosiery knitting machine, particularly for a machine for knitting stockings, comprising a cylindrical weight in the form of a hollow cylindrical body having gripping means at its upper end for engagement with fabric knitted by the machine and vertically slidable in a hollow tube arranged below the needle cylinder of the machine, a supporting member for said weight, and a lifting mechanism for raising and lowering the supporting member within the tube, whereby the supporting member together with the hollow cylindrical body can be raised to a position where the latter can be gripped onto fabric being knitted and the supporting member can be lowered leaving the hollow cylindrical body depending from the fabric, and wherein engagement of the hollow cylindrical body with the supporting member, as during the raising thereof or when the hollow cylindrical body has descended down the hollow tube as the fabric progresses, causes release of the gripping means to permit fabric to be secured thereto or detached therefrom.

The invention will be described further, by way of example, with reference to the accompanying drawings in which:

Fig. 1 is a cross-sectional side elevation of a circular knitting machine for hosiery incorporating a tensioning device in accordance with the invention, said device being shown in the lifted position as during the formation of the welt of a stocking;

Fig. 2 is a fragmentary side elevation, partly in section, showing a supporting member of the tensioning device, in its lowermost position;

Fig. 3 is an elevation similar to Fig. 2 with certain parts omitted, showing the supporting member extended to its uppermost position;

Fig. 4 is a cross-sectional side elevation on yet a larger scale of a cylindrical weight forming part of the tensioning device;

Fig. 5 is an elevation, partly in section, showing details of a mechanism for lifting the supporting member of Figs. 2 and 3, and

Fig. 6 is a plan view showing part of Fig. 5 and a control therefor.

In the drawings a circular knitting machine for hosiery of the type having a rotating needle-cylinder and stationary locking devices is shown, and only the parts thereof which are essential to the understanding of the invention have been illustrated.

A cylinder 1 locates a plurality of needles 2 driven by a conventional cam device (not shown). The cylinder 1 is fitted on a hollow column 3 which has integral therewith, near the lower end, a toothed wheel 4 which, by a transmission, not shown herein, has a rotary or oscillatory motion imparted thereto from a mainshaft 5. A disc 6 which carries hooks 7 is rotated in synchronization with the cylinder 1, and the hooks 7 are actuated in known manner by cams (not shown) for knitting a double border or welt at the beginning of a stocking. A thread 8 is fed to the needles 2 by thread guides 9.

A hollow tube 10 extends from a point approximately level with the top of the cylinder 1 inside said cylinder down to the base of the machine, and has at its upper end, an annular lip 10a protruding towards the interior. A solid frame 11, supported by feet 12, supports all the elements of the machine.

The parts so far described are common to nearly all machines of thekind to which the invention is applicable. Their operation, therefore, is well known. if

of the mechanism The tensioning device according to the invention comprises basically three parts, namely:

(a) A cylindrical weight,

(b) A supporting member for said cylindrical weight, and

(c) A lifting mechanism with driving means for lifting the weight soas to permit it to be attached to a partly knitted stocking when the welt has been knitted.

The cylindrical weight is illustrated in Fig. 4 and comprises a hollow cylindrical body 13 which has integral therewith an internal tubular guide 14 for a spindle 15 and a bush 16 which surrounds the spindle 15 and is capable of axial sliding movement relative thereto.

The spindle 15 and the bush 16 can therefore slide with respect to each other and they are also capable of axial movement relative to the internal tubular guide 14. The spindle .15 is of smaller diameter at its upper end than at its lower end, and said upper end is located in a through hole 17 in the internal tubular guide 14.

A small helical spring 19 engages a shoulder 18 separating the smaller and larger diameter portions of the spindle 15, and near its lower end said spindle 15 is provided with an annular groove 20 which is'partly cylindrical and partly frustoconical. A disc 22 is secured to the upper end of the spindle 15 by means of a screw 21, said disc 22 having 21 depending spigot 23 which can slide over the external cylindrical surface of the internal tubular guide 14 and is guided thereby.

The disc 22 has a peripheral conical edge 24 capable of resting upon and of co-operating with a corresponding surface on a thickened rim 25 of the hollow cylindrical body 13 and the latter is internally fitted with guiding gills 26, the purpose of which will be described later.

The bush 16 substantially surrounds the larger diameter lower part of the spindle 15 and is guided by the internal tubular guide 14 and by a washer 27 afiixed to said guide 14. The washer 27 surrounds the bush 16 at a reduced diameter portion thereof, said reduced-diameter portion being defined by two shoulders 28 and 29 located near the opposite ends of the bush 16. Axial movement of the bush 16 within the internal tubular guide 14 is therefore limited by engagement of the shoulders 28 and 29 with the washer 27.

A second larger helical spring 30 is located in the internal tubular guide and engages at one end on the upper end of the bush 16 and at the other end against the upper part of the internal tubular guide 14. This larger helical spring 30 surrounds the upper portion of the spindle 15 and the small helical spring 19, and serves to urge the bush 16 downwards as viewed in Fig. 4.

At the lower end of the bush 16 a detent lever 32 is pivoted at 31, and a nose 33 on the detent lever 32 is capable of moving into a slot in the bush 16 to engage the groove 20 in the spindle 15. The shape of nose 33 corresponds to that of the groove 20. A depending arm 34 of the detent lever 32 projects below the lower end of bush 16, and a small tension spring 35 secured at one end to the arm 34 and at the other end to the lower end of the bush 16 tends to move the detent lever 32 to the position in which its nose 33 engages the groove 20 of the spindle 15, as shown in Fig. 4. As can be seen in Fig. l, the hollow cylindrical body 13 is accommodated in the hollow tube 10 and its outside diameter is slightly smaller than the inside diameter of said hollow tube 10 to permit vertical movement within the hollow tube 10.

The supporting device for the hollow cylindrical body 13 (see Figures 1, 2 and 3) is also accommodated in the hollow tube 10. This supporting device comprises a series of articulated rods arranged in the manner of socalled lazy tongs, two upper rods 36 and 37 being articulated at 38 and supporting a sleeve 39 which is also pivoted at 38. Surrounding the sleeve 39 is a disc-like platform 40 which is capable of a vertical sliding movement along the sleeve 39 and which rests with its lower surface i guide lugs 53b (Fig. 2).

engaging on ears 41, 42, provided on the rods 36 and 37 respectively.

The diameter of platform 40 is substantially equal to that of the cylindrical body 13, whilst the internal diameter of the sleeve 39 is approximately equal to the outside diameter of the bush 16 of the hollow cylindrical body 13.

A rod 43, which together with a rod 44 forms a lower pair of rods of the lazy tongs supporting member, has secured thereto, by a pivot 45, a lever 46 having two arms of different length, while the rod 44 is fitted with a pin 47.

The longer arm of the lever 46, in the neighbourhood of the pivot 45, is cut back at its lower edge to provide a notch 48 capable of being engaged by the pin 47 on the rod 44 when the lazy tongs supporting member is at its maximum extension in vertical direction. (Figure 3 shows the position in which the pin 47 is about to engage in the notch 48.) When the pin 47 is in engagement with the notch 48, the whole system formed by the rods is locked in its extended position. The lower rods 43, 44 are pivoted at 49 where an arm 50 is also pivoted, the lower end of the arms!) being shaped as a hook 51. Also suspended at 49 isa hollow collar 53a, through which the hook 51 of the arm 50 extends. The collar 53a has two Secured to the bottom of the hollow tube 10 is a fixed catch 52 capable of engaging with the hook 51, the latter being biassed to the engaged position by a compression spring 53 engaging against the inner surface of the collar 53a. The hook 51, when engaged with the fixed catch 52, serves to anchor the supporting member at the bottom of the hollow tube 10.

A peg 54, secured to the lever 46, co-operates with the upper part of the arm 50 to disengage the hook 51 from the fixed catch 52, as will later be described in detail.

As the overall width of the system of articulated rods forming a lazy tongs supporting member, when they are closed up or disposed closely adjacent to one another as shown in Fig. 2 is much greater than the diameter of the hollow tube 10 within which the whole system is housed, the hollow tube 10 has, in its lower portion, vertical slots 55 through which said rods project outwardly. The aforementioned guide lugs 5312 on the collar 53a slide within the vertical slots 55 of the hollow tube 10 and consequently act to locate the system of rods relative to the tube 10. A knock-off arm 74 is affixed to the frame 11 of the machine, near to the bottom of the hollow tube 10, and this is capable of co-operating with the lever 46 when the system of rods moves towards the bottom of the tube 10.

Two cords, S6, 57, are each affixed at one end by screws 58, 59, to a rocking arm 58a which, in turn, is fulcrummed at 59a to the system of rods, and these cords serve to lift the whole system of rods constituting the supporting member and the hollow cylindrical body 13. A mechanism for winding the cords 56, 57, cgmprises a drum 60 which is rotatable about its own axis, is axially slidable Within the frame 11 of the machine and is arranged coaxially below the main shaft 5.

To the upper end of the drum 60 is secured one half 61 of a dog-clutch, the other half 62 of the dog-clutch being secured to the lower end of the main shaft 5. At the lower end of the drum 60 is a ratchet wheel 63 engaged by a pawl 64 which is pivoted at 65 to the frame 11 and urged into engagement with the ratchet wheel 63 -by a pawl spring (not shown). An extension of the pawl 64 contacts a roller 66 mounted at one end of an actuating arm 67, the other end of the arm 67 being mounted on an arbor 68. A follower arm 69 is secured to the arbor 68 and has a pointed end 70 which contacts the surface of a main drum 71 of the machine (see Fig. 6).

A fork 75 pivotally mounted at 76 on the frame 11 encircles the drum 60 and is capable of displacing said drum in a vertical direction. Two prongs of the fork 75 are connected to each other by a small cross-bar 77 with which a latch 78, pivoted in the frame 11 at 79, is capable of engagement. The latch 78 is biased by a spring (not shown) so as to engage the cross-bar 77. i The pawl 64, when it rotates in an anti-clockwise direction about its fulcrum 65 as viewed in Fig. 6, is capable of causing disengagement of the latch '78 from the crossbar 77, by moving against the end of an abutment screw 80 associated with the latch 78.

The fork 75 is integral with a bar 81 which extends beyond its pivot 76 and is subject to the influence of a vertical tension spring 82. This spring 82 tends to depress the bar 81 and consequently to lift the fork 75. To the free end of the bar 81 is pivoted a bell-crank lever 83 the movement of which is limited by the engagement of studs 84 in an elongated aperture 85 in said bell crank lever 83. The free end of the horizontal portion of bell crank lever 83 is positioned in the path of and co-operates with the rocking arm 58a of the system of rods and constitutes an arrester for the lifting motion of said system.

Within the drum 60, and centrally disposed in the lower end thereof, is screwed a threaded rod 86, to the lower end of which is secured a small plate 87 which is apertured to fit over a vertical guide rod 88. A screw 89 projects through the plate 87 and is capable of being adjusted with respect thereto, and upon vertical movement of the threaded rod 86 this screw 89 can abut against a surface 90 of the frame 11. The cords 56 and 57 which are each afixed at one end to the rocking arm 58a of the system of articulated rods, are guided by sheaves 91 and 92, and are secured at their other ends to the drum 60.

The hollow tube 10, besides having the vertical slots 55 for accommodating the rods of the supporting member, is provided with openings 93 which permit inspection of the apparatus and extraction of stockings on completion of their manufacture.

The operation of the device hereinbefore described is as follows:

Considering the apparatus in the condition wherein the knitting machine has just completed the manufacture of a stocking, which has been removed and is just starting its cycle for manufacturing another stocking, the hollow cylindrical body 13 rests on disc-like platform 40 of the system of rods, while the latter occupies its lowermost position, as shown in Fig. 2, and is anchored at the bottom of the hollow tube by engagement of the hook 51 with the fixed catch 52. The cylinder 1 performs the preliminary revolutions in order to knit the border or welt of the stocking. The main drum 71, which performs one complete revolution only during the knitting of a whole stocking, and which rotates fractionally, moves until a protrusion 72 thereon engages under the pointed end 70 of the follower arm 69 and, by pivoting said follower arm 69, the arbor 68 and the actuating arm 67, causes the pawl 64 to swing about its pivot 65. The pawl 64, by engaging the latch 78, causes the latter to disengage from the cross-bar 77 so that the fork 75, under the influence of the vertical tension spring 82, is raised and lifts the drum 60, connecting this drum through the clutch halves 61, 62, to the main shaft 5 which is constantly rotating. The drum 60, therefore, also rotates and winds in the cords 56 and 57 thereby lifting the system of rods and the hollow cylindrical body 13.

The system of rods extends in a vertical direction and, when it reaches the position shown in Fig. 3, the notch 48 of lever 46 is engaged by the pin 47 thus making the whole system rigid, while the peg 54 causes a slight rotation of the arm 50 about its pivot 49 to disengage the hook 51 from the fixed catch 52, with the result that the system of rods is no longer anchored to the bottom of the hollow tube 10. As it rises further the system of rods is introduced into cylinder 1 and thus carries the hollow cylindrical body 13 to the position shown in Fig. 1, where the upper edge of body 13 abuts against the annular lip 10a of the hollow tube 10. The sleeve 39 is borne by the two upper rods 36, 37, and is lifted a greater extent than is the disc-like platform 40 so as to cause'the bush 16, which is resting on the sleeve 39, and the spindle 15 which is locked to the bush 16 by engagement of the nose 33 with the annular groove20, to be lifted with respect to the hollow cylindrical body 13 against the action of the larger helical spring 30, until the shoulder 29 on the bush 16 comes into contact with the washer 27. Thus the disc 22 is lifted relatively to the hollow cylindrical body 13 (see Fig. 1).

During its rotation, the drum 60by its engagement with the threaded rod 86 causes the latter to rise and with it the small plate 87. When the adjustable screw 89 comes into contact with the surface 90, the threaded rod 86 is arrested in its vertical movement and consequently the drum 60 travels down the latter. This causes the disengagement of the clutch halves 61 and 62 and drum 60 ceases to rotate. In the meanwhile the main drum 71 has performed :a slight rotational movement so that the pointed end 70 of the follower arm 69 becomes disengaged from the protrusion 72. The pawl 64 then engages the ratchet wheel 63 thus preventing any rotation of the drum 60 in an anti-clockwise direction as viewed in Fig. 6. At the same time, the latch 78 is again able to lock the fork 76 in its depressed position. A safety contrivance to arrest the lifting movement of the hollow cylindrical body 13 when it has been lifted to a suitable height, is constituted by the bell crank lever 83. When, in fact, the system of rods has reached the desired height, the rocking arm 58a encounters the bell crank lever 83 and lifts it, and, by simultaneously lifting the bar 81, causes the fork 75 to be depressed and consequently disengages the drum 60 from the main shaft 5 and arrests its rotation,

-In this condition the knitting machine continues the formation of thewelt of the stocking and delivers the fabric as his knitted to the interior of the hollow cylindrical body 13. Introduction of the fabric into the body 13 is facilitated by the guiding gills 26 provided in the hollow cylindrical body 13 for that purpose. As soon as the double welt has been completed and is attached to the leg of the stocking, the main drum 71 again effects a slight rotation, bringing a second shallower protrusion 73 under the pointed end 70 of the follower arm 69. The height of the second protrusion 73 is smaller than the height of the protrusion 72, so that the rotation of the arbor 68 and of the pawl 64 are slightly less than before and just sufficient to disengage the ratchet wheel 63 but not enough to disengage the fork 75.

As the drum 60 is now free to rotate, the system of rods can fall under its own weight. When the system has dropped to such an extent that the lever 46 encounters the knockoff arm 74, the notch 48 is disengaged from the pin 47 and the system of rods can collapse completely to the condition illustrated in Fig. 2, wherein the hook 51 engages the fixed catch 52. It is to be noted, however, that only the supporting device has dropped, while the hollow cylindrical body 13 has engaged the stocking being knitted and remains near the upper end of the hollow tube 10. Such engagement of the body 13 occurs when the support falls. The larger helical spring 30 is able to snap the bush 16, the spindle 15, and the disc 22 downwards relative to the body 13, thus gripping the stocking between the peripheral conical edge 24 and the thickened rim 25 so that the hollow cylindrical body 13 depends from the stocking. The hollow cylindrical body 13 by its own weight, keeps the fabric of the stocking under tension as it is being knitted and follows all the movements thereof, such following of the movements of the stocking being knitted is facilitated by the fact that the hollow cylindrical body 13 is of short axial length. On completion of the knitting of the stocking, the knitting machine stops and by this time the cylindrical body 13 has descended to a level slightly above the upper end of the lazy tongs supporting member which is in its collapsed position as shown in Fig. 2. The stocking is detached from the needles 2 of the cylinder 1, the hollow cylindrical body 13.is allowed to :drop freely inside the hollow tube 10. The first parton vthe body 13 which swinging about its pivot 31, disengages the spindle 15 from the bush 16.

The bush 16, urged by the larger helical spring 30, is pushed slightly downwards relative to the hollow cylindrical body 13 until the shoulder 28 thereon encounters the upper surface of the washer 27. The spindle 15 is now free to slide within the bush 16 and the stocking can beremoved easily, since the disc 22 can now be lifted, carrying with it the bush 16, until the small helical spring 1 encounters the upper end of theinternal tubular guide 14. After the stocking has been removed from :the hol- V low tube 10 through one of the openings 93, the above described cycle is repeated duringthe knitting of the next stocking.

I claim:

1. In a circular knitting machine havinga needle cylinder; a tensioning device comprising a hollow tube arranged below said needle cylinder, a cylindrical weight in the form of a hollow cylindrical body verticallyslidable in said hollow tube, means for gripping fabric onto said hollow cylindrical body including an internal tubular guide disposed in said body, a bush vertically displaceable in said internal tubular guide, a spindle vertically displaceable in said bush, a disc mounted on said spindle and disposed above the upper end of ,said hollow cylindrical body, a helical spring surrounding said spindle and acting on said bush to urge it downwards and detent means for locking said spindle tosaid bush, asuppor'ting member for said weight, and a lifting mechanism for raising and lowering said supportingmernber withinsaid hollow tube, whereby said supporting member together with said hollow cylindrical body canbe raised to aposition just below said needle cylinder wherein it can be gripped onto the knitted fabric and said supporting member can be lowered to leave said hollow cylindrical body depending from the fabric, said supporting member cooperating with said detent means during the raising of said hollow cylindrical body and when said hollow cylindrical body has descended down said hollow tube'with progression of the fabric to release thespindle from the bush for allowing said disc to be raised and permitting fabric to be secured to or detached from said hollow cylindrical body.

2. In a circular knitting machine having a needle cylinder; a tensioning devicecomprising a hollow tube arranged below said needle cylinder, a cylindrical "weight in the form of a hollow cylindrical body vertically slidable in said hollow tube, means for gripping fabric onto said hollow cylindrical body including .aninternal tubu lar guide disposed in said hollow cylindrical body,a slotted bush vertically displaceable in said internal'tubular guide, a spindle vertically displaceable in said bush and having an annular groove, a disc mounted on said spindle and disposed above the upper end of said hollow cylindrical body, a helical spring surrounding said spindle and acting on said bush to urge it downwards, a detent lever pivoted to said bush, a nose on said detent lever capable of extending through the slot in said bush to engage with said annulargroove and lock said spindle to said bush, and a depending arm on said detent lever, a supporting member for said weight, and aJlifting mechanism for raising and lowering said supporting member "within said hollow tube, whereby said supporting member together with said hollow cylindrical body can be raised toaposition just below said needle cylinder wherein .it'can'be grippedont-o the knitted fabric and said supporting member can be lowered to leave said hollow cylindrical body depending from the fabric, said supporting member co-operating with said depending arm-during the raising of said hollow cylindrical body and when said hollow cylindrical body has descended down said tube with progression of the fabric to release the spindle from the bush for allowing the disc to be raised and permitting fabric to be secured to or detached from said 1101- low cylindrical body.

3. In a circular hosiery knitting machine having a needle cylinder; .a tensioning device comprising a hollow tube arranged below said needle cylinder; a cylindrical weight in the form of .a hollowcylindrical body vertically slidable in said hollow tube; means for gripping fabric onto said hollow cylindrical body including an internal tubular guide disposed in said hollow cylindrical body, a slotted bush vertically displaceable in said internal tubular guide, a spindle vertically displaceable in said bush and having an annulargroove, a disc mounted on said spindle and disposed above the upper end of said hollow cylindrical body, a helical spring surrounding said spindle and acting on said bush to urge it downwards, a detent lever pivoted to said bush, a nose on said detent lever capable of extending through the slot in said bush to engage with said annular groove and lock said spindle to said bush anda depending arm on said detentflever; a supporting member for said weight including a plurality of rods pivoted together in the form of lazy tongs carrying at the upper end a sleeve with a disc-like platform surrounding said sleeve and vertically slidable thereon; and a liftingmechanism for raising and ,lowering said supporting member within said hollow tube whereby said hollow cylindrical body by engagement of the disc-like platform therewith can be raised to a position just below said needle cylinder, said sleeve cooperating with the bush to raise said disc and permit fabric to be attached to said hollow cylindrical body and whereby said supporting member can be lowered to leave said hollow cylindrical body depending from the fabric, and a knock-off arm engageable by said depending arm when the hollow cylindrical .body descends down the hollow tube with progression of the fabric to release said spindle from said bush to permit said disc to be raised and the fabric released from said hollow cylindrical body.

4. In a circular hosiery knitting machine, the tensioning device defined in claim ,3 further includingmeans for .anchoringsaid supporting member at the bottom of said hollow tube when it has been lowered, and for releasing such means during raising of the supporting member when said articulatedrods have been extended to their full extent.

5. In a circular hosiery knitting machine, the tension- .ing device defined in claim 4 further including means for preventing articulation of s-aid-rods when they have been extended to their full extent.

References Cited in the file of this patent UNITED STATES PATENTS 2,729,032 Tew Jan. 3, 1956 

